The present invention relates generally to the field of wireless communications systems, and specifically to Location Services for use with General Packet Radio Service.
Global System for Mobile Communications (GSM) is a global standard for wireless telecommunications. Various GSM defined standards (GSM 900, GSM 1800, GSM 1900, etc.) have been deployed to provide cellular radiocommunication services in many countries around the world. The GSM standard was developed primarily for voice communications, but is also used to provide circuit-switched data services that require a continuous connection. The General Packet Radio Service (GPRS) is a recent extension of the GSM standard to provide packet switched data services to GSM mobile stations. Packet-switched data services are used for transmitting small amounts of data or for data transfers of an intermittent or bursty nature. Typical applications for GPRS include Internet browsing, wireless e-mail, and credit card processing. GPRS is described more fully in “3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; General Packet Radio Service (GPRS); Service description; Stage 2 (Release 1999),” the disclosure of which is incorporated herein by reference.
The GSM standard is capable of providing a variety of information services to subscribers. Location Services (LCS) is one example of an information service that GSM provides. LCS allows a subscriber or client to obtain or determine the location of a GSM mobile station operating within the GSM network. The location may be determined by the network, based on measurements supplied by the mobile station, or may be determined by the mobile station itself and communicated to the network. Various approaches to position estimation may be used, including Uplink Time of Arrival (TOA), Enhanced Observed Time Difference (E-OTD), and assisted Global Positioning System (GPS). LCS is described more fully in “Digital cellular telecommunications system (Phase 2+); Location Services (LCS); (Functional description)—Stage 2 (GSM 03.71 version 8.0.0 Release 1999).”
In the current GSM standard, a centralized server known as the Serving Mobile Location Center (SMLC) manages the overall coordination and scheduling of resources required to perform positioning of a mobile station. In order to perform these functions, the SMLC must exchange information with other entities within the network, such as the mobile station and/or a Location Measuring Unit (LMU). This location information may be the position of the mobile station, measurements from which the position of the mobile station may be determined, or data otherwise useful in determining the position of the mobile terminal. For instance, the location information may be that discussed in “3rd Generation Partnership Project; Technical Specification Group GSM EDGE Radio Access network; Mobile Station (MS)—Serving Mobile Location Centre (SMLC) Radio Resources LCS Protocol (RRLP)” (Release 1999, v8.3.1), incorporated herein by reference.
Communication protocols permit the orderly exchange of information between nodes or entities within a network. Communication protocols to support LCS information exchange in conventional circuit-switched GSM networks have been developed. In contrast, communication protocols for GPRS networks are still in development and have not been finalized. Thus, many aspects of the communication protocol needed to support LCS in a GPRS network remain unresolved.